<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            position: absolute;
            left: 0;
            width: 100px;
            height: 100px;
            background-color: red;
        }
        span{
            display: block;
            left: 0;
            top: 200px;
            width: 150px;
            height: 150px;
            background-color: purple;
            position: absolute;
        }
    </style>
</head>
<body>
    <div></div>
    <span></span>
    <script>
      //简单动画函数封装 obj目标对象 target目标位置
      function animate(obj,target){
        var timer= setInterval(function(){
            if(obj.offsetLeft>=target){
                //停止动画 停止定时器
                clearInterval(timer);
            }
           obj.style.left=obj.offsetLeft+1+'px';
        },30)
      }
        var div=document.querySelector('div');
        var span=document.querySelector('span');
        //调用函数  
        animate(div,300);
        animate(span,500);

    </script>
</body>
</html>